Abstract: Gangou debris flow is located in Hongse village, Hongkou town of Sichuan province. A number of debris flows have occurred after the Wenchuan earthquake. Debris flow caused by the torrential rain in June 9 of 2013 destroyed the house of resident and flooded the fields; meanwhile, there is still a lot of loose material in the ditch, which will threaten the resettlement spots and road. Based on the material from the disaster emergency investigation and the risk evaluation method of the debris flow on single channel, this paper studies formation conditions, development characteristics, susceptible degree and risk of the debris flow. At last, the result shows that both the hazard susceptibility and fatalness are on an intermediate level, still posing a threat to life, property of local residents, as well as the surrounding traffic.